Efficient Interference Detection in 3D Animations of Simulated Construction Operations

This paper presents research that led to the design and implementation of efficient interference detection methods that can be used to identify and report undesirable conflicts that occur among static (e.g. structure in-place, idle equipment), dynamic (e.g. active machines and workers), and abstract (e.g. hazard spaces) construction resources in 3D animations of discrete-event simulation models. The designed methods are implemented in a software tool called C-Collide that integrates as an add-on with the VITASCOPE visualization system. Common types of clashes that can occur on real construction sites and that C-Collide can identify beforehand in 3D process animations include 1) intersection among physical in-place components (i.e. design interferences), 2) intersection among in-place components, components in transit, and/or pieces of moving equipment during construction (i.e. constructability interferences), 3) craft interferences and accidents (e.g. collision between two pieces of equipment operating in the same area), and 4) space intrusions (e.g. any resource worker or equipment encroaching arbitrarily shaped hazard or protected areas of the jobsite). Animations of simulated construction processes are computationally demanding because elapsed visualization time is always related to the elapsed wall clock time by a distinct viewing ratio. This viewing ratio must be strictly maintained regardless of the number of screen updates between subsequent simulation time instants. Thus, to depict smoothly moving scene objects and to avoid jerkiness in the presented graphics, the screen must be updated at an acceptable refresh rate (ideally >= 24 fps). The impact of the collision detection computations on this frame rate must thus be minimal. Computational efficiency in the designed interference detection methods was therefore of paramount importance in C-Collide. In addition, this efficiency could not be traded off against accuracy. In order to achieve this, the authors capitalized on advanced documented algorithms for efficient collision detection between arbitrarily moving 3D geometric objects to design mechanisms for interference detection, control, and response in construction process visualizations. C-Collide’s interference detection capabilities dynamically check each motion of VITASCOPE scene objects to determine if any pairs of scene objects interfere undesirably. This provides a lucid understanding of all object motions and potential interferences in any area of activity on a simulated construction job site.